This invention generally relates to cigarettes, and also to cigars and small cigars, embodying in their fore tip, i.e. at the end opposite to the end fitted with a filter tip, or at any rate opposite to the end which is kept between the lips, means for the lighting thereof, without the need for recourse to exterior flame sources, as e.g. matches, lighters and the like.
In more detail, this invention relates to improvements made in and to cigarettes having an individual lighting means of the type comprising an essentially annular lighting member fitted at the fore end of the cigarette tube, usually made of paper, and having a composition which is capable of being lighted at least in a point of its contour by rubbing against a rough surface in a manner similar to the tip of a normal match, the composition containing a small amount of phosphor to ensure a quick spreading of combustion to the whole contour of the lighting member, thereby forming a narrow incandescent ring which lasts for a short time but which has sufficient heat to start the lighting of tobacco at the end of the cigarette.
Such cigarettes are already known in the art. In particular, a cigarette fitted with a lighting means of the above described type is disclosed and shown in U.S. Pat. No. 3,262,456, which includes a comprehensive list of patents which practically represent the development of technology in the field of the invention. Reference is therefore made to such patents for a more complete knowledge of precedents, premises and final aims of this invention.
However, such cigarettes, though enjoying a widespread diffusion, are not universally accepted, for several different reasons. One reason is cost, since resourse must be made to material and compounds by which the manufacturing costs are materially increased. Another reason is that the lighting operation, to be performed by rubbing a pre-established, narrow point of the contour of the cigarette end against a rough surface, is somewhat difficult and requires attention and experience on the part of the smoker. A further reason is the need of having special mechanical means and equipment for the precise and accurately located application of the lighting means to the cigarette, or more precisely to a thin paper strip by which the cigarette tube is formed, particularly in view of the very high speed of production of cigarettes. Such extremely high production speeds, of an order of many thousands of cigarettes, even with filter tips, per minute, have practically made impossible a corresponding application of lighting means, due to the difficulties encountered in the exact synchronization and accurate positioning of the various elements.
Moreover, in spite of continuing improved technical solutions proposed, the required degree of efficiency is not yet practically attained by such lighting means. The prior art, inclusive of its most advanced development as disclosed in U.S. Pat. No. 3,262,456, has always been confronted with the difficulty of solving conflicting technical problems, namely, the need for ensuring an extremely quick spreading of combustion from the initial point or narrow zone of lighting across the whole contour of the cigarette end, as required for a complete and consistent lighting of tobacco, and the need for maintaining the thus formed incandescent ring for a time sufficiently long (e.g. of an order of one second) to obtain a good priming of combustion to the tobacco.
The above two requirements are obviously directly in conflict. As a matter of fact, when considering the very small amounts of combustible and oxidizing materials that can be tolerated in the lighting means, those compositions which ensure a lively spreading of flame cannot maintain the flame long enough to ensure combustion of the tobacco. Conversely, a compound which in very small amounts and cross-sections would be able to maintain a flame long enough for combustion would not provide the required quick spreading of combustion.